1. Field of the invention
The present invention relates to a method and apparatus for switching roving bobbins in a spinning frame. More specifically, the presnet invention relates to a roving bobbin exchange method and apparatus in a spinning frame in which two front and rear rows of bobbin hangers are arranged on a creel, roving bobbins are hung on the bobbin hangers of the two front and rear rows, and spinning is carried out by guiding rovings to a drafting zone from the roving bobbins.
2. Description of the Prior Art
Ordinarily, bobbins supplied from a roving process, which are to be mounted on a creel of a spinning frame, have a full bobbin diameter larger than the spindle pitch of the spining frame. Accordingly, roving bobbins are arranged in two rows in the longitudinal direction of the machine frame at an interval two times as long as the spindle pitch, and roving rods or roving guides are arranged between the front and rear rows of the bobbins to guide rovings from the roving bobbins. The roving bobbins are hung in the upper portion of the machine frame at the respective positions above the height of a worker. A recent tendency is to utilize a full bobbin having a very heavy weight exceeding 3 kg. Accordingly, in the roving bobbin exchange operation in the spinning frame, bobbins having a heavy weight must be lifted up to respective positions higher than the height of the worker, which operation is very troublesome. Furthermore, since several hundred (ordinarily about 400) full bobbins and the same number of empty bobbins must be handled for each spinning frame at each roving bobbin exchange operation, the roving bobbin exchange operation requires heavy labor.
Considerable research has been made foward the development of a method and apparatus for switching exhausted roving bobbins with full ones in a conventional spinning frame. For example, the invention disclosed in Japanese Examined Patent Publication No. 48(1973)-27209 provided a method of simultaneously exchanging a plurality of exhausted roving bobbins in a block with full ones utilizing a mechanical means. In this method, roving creels of the frame are divided into a plurality of blocks along the lengthwise direction of the spinning frame. The invention disclosed in Japanese Examined Patent Publication No. 54(1979)-3978 provided a semi-automatic method for exchanging exhausted roving bobbins with full ones, wherein roving creels are capable of displacement between their spinning and standby positions and wherein the roving bobbin exchange operation is manually carried out at the standby position.
The problem regarding the removal of exhausted bobbins from the bobbin hangers and mounting of full bobbins thereto can be solved by these prior arts. The operations of cutting rovings between bobbins held by the bobbin hangers and the corresponding draft parts, catching a free end portion of roving from each full bobbin held by the bobbin hangers, threading the free end portion of each roving into the draft parts of the spinning frame, piecing of yarn at the ring twisting and winding mechanism, etc., however, have to be manually effected.
Experience has shown that such manual operations are much more difficult for the bobbin hangers of the rear row than a front row. They have therefore sought to practically solve the problem due to the tworow arrangement of bobbin hangers.